1. Field of the Invention
The present invention relates to an optical device and a projector.
2. Description of Related Art
Conventionally, there has been known a projector having a plurality of optical modulators that modulate a light beam irradiated from a light source in accordance with image information to form an optical image, a color-combining optical device that combines and irradiates the light beam modulated by the optical modulator, and a projection optical device that projects the light beam combined by the color-combining optical device in an enlarged manner.
As the optical modulator, for instance, an arrangement including an active matrix driven liquid crystal panel that has an electrooptic material such as a liquid crystal sealed between a pair of boards, and a polarization plate that only transmits light beams having a predetermined optical axis is widely used.
Specifically, the pair of boards included in the liquid crystal panel has: a drive board disposed on a light-irradiation side and provided with a data line, a scan line, a switching element, a pixel electrode, etc. for applying driving voltage to the liquid crystal; and an opposing board disposed on a light-incident side and provided with a common electrode, a black mask, etc.
When the light beam irradiated from the light source is irradiated on the liquid crystal panel, the liquid crystal panel tends to be subjected to the temperature rise due to light absorption of the data line and the scan line formed on the driving board and the black matrix (translator's comment: black mask) formed on the opposing board as well as light absorption of the liquid crystal layer. Further, among the light beams irradiated from the light source and transmitted through the liquid crystal panel, the light beam not having the predetermined optical axis is absorbed by the polarization plate, which easily causes generation of heat on the polarization plates.
Therefore, for projectors having such optical modulators therein, an arrangement having a cooling device using a cooling fluid has been proposed for restraining temperature rise of the optical modulator (see, for example, Patent Document 1: JP Hei 3-174134A).
The cooling device disclosed in the Patent Document 1 is formed with a case having a substantially rectangular parallelepiped shape with its opposing sides opened, which includes a cooling chamber adapted to seal a cooling fluid therein. A liquid crystal panel is disposed on one side of the opposing sides while a polarization plate is disposed on the other side, so that openings of the opposing sides are closed with the liquid crystal panel and the polarization plate to form the cooling chamber. With such arrangement, the heat generated on the liquid crystal panel and the polarization plate due to the light beam irradiated from the light source is directly released to the cooling fluid.
However, in the cooling device disclosed in the Patent Document 1, since the cooling fluid is sealed in the cooling chamber, the cooling fluid is easily heated by the heated liquid crystal panel and polarization plate, so that the heated cooling fluid is stayed in the cooling chamber.
Therefore, temperature difference between the optical modulator and the cooling fluid becomes small, which makes it difficult to cool the optical modulator efficiently.
An object of the present invention is to provide an optical device capable of efficiently cooling an optical modulator with a cooling fluid and a projector.